XL Soda Bottle Rocket Engines (Static Testing)

[Applause] [Music] [Applause] [Music] Wow [Music] [Applause] [Music] this video was sponsored by Mel science you can get Mel chemistry sets and experiments delivered right to your door get 25% off by using the link in the video description below more on that later hi everyone in this video I thought we would try playing around with some stationary bottle rocket testing I really like my propane bottle rocket projects and I've wanted to try using larger Rockets than standard 1 or 2 liter bottles this means I have to stick them together I first thought I would do this in the same way as it's done for water rocketry you cut the bottles in half dip one in hot water so it shrinks enough to fit into the other bottle then you rough up the plastic with sandpaper and use a strong glue to stick them together permanently if you do this right it works great but for propane rockets it's maybe not necessary so for some of my bottles I took the easy way out and just used tape it will be interesting to see if this holds up to the pressure something else we'll be looking at is the location of ignition with smaller rockets I haven't had to think much about where in the bottle I'm igniting the fuel because they're small fire pretty much washes through the whole bottle before it ever leaves the launch pad with these larger bottles that might not be the case I expect we'll see some interesting differences between rockets that are ignited near the open end compared to further away ok first test let's see what happens in this double size bottle if we ignite it with an open end to simulate what it would be like if it were a rocket flying through the air and we ignite it roughly in the middle since we are igniting this in the center of the bottle I expect the flame to travel outwards like a bubble expanding evenly in pretty much every direction but we'll see what it looks like in slow motion okay so we are going to start filling this bottle with the propane and air mixture from a regulated propane torch and I'll do that from the back of the bottle to the front which is why the bottle is just barely hanging on to the end of this pipe right now and then when I'm ready to fire I'll just move this backwards and we'll see how it does okay here we go all right let's see what the high-speed footage looks like oh wait a minute that is not what I expected that is going to be really tough to diagnose exactly what's going on we're gonna do this a few more times and compare the results okay we'll move this back it's in the firing position and let's see what happens to my eyes this looked pretty much exactly the same to the first shot so let's see if the high-speed tells the same story this is so much cooler than I anticipated we definitely do not see a bubble form at the point of ignition and maybe that's due to the open end on the bottle my usual bottle rockets when I was firing those off the launcher that closes the mouth of the rocket so it's a closed system when it ignites resulting in equal pressure on the inside of the bottle I expect that's why I see a bubble form in my bottle launcher shots but these static tests behave totally differently the next thing I might try is to maybe put a plug in the end of these bottles I bet then we'll see that bubble form all right this is awesome let's get one more shot like this and then move on to the next tests ready three two one ooh slower burn on it that time well the slower burn on it probably means that that mix was a little bit propane rich I probably have to turn the torch down because having the high flow rate sometimes it doesn't carry quite enough air in to mix with the propane so pretty clearly that open end on the bottle creates a big effect in how the flame travels through the bottle it ignites much more quickly toward that open end because that's the direction it can move in the fastest because the lowest pressure is toward that nozzle and it takes a much longer time to slowly travel into the back of the bottle where it's got that closed end and pressure from the combustion is actually making that a high-pressure area back there it's creating a barrier that causes the flame to travel more slowly okay now I've made a plug for the end of these static tests and now I think we're going to get a little bit closer result to what I expected I think once I have this end partially plugged I actually have made this so it's going to launch out after we ignite this bottle but I think in the mean time we're gonna see that ball of fire expanding slowly outwards from the center of this rocket just got to make sure there's nothing in that direction that I'm gonna be afraid of this hitting when it launches out at the end of this bottle Wow oh this is gonna be cool high speed right here Wow just look at like that Lake of Fire effect going on on the bottom of the bottle it's actually doing this rotational thing where it's it's kind of flowing from the high pressure back of the bottle it's flowing through the bottom of the bottle which is interesting toward that nozzle and I wonder if that's that must be because the uncombusted fuel that's underneath that wall of fire is colder it's more dense than the flame that's going on above it and so that would cause it to to settle lower than what has already been combusted and rotate toward the nozzle on the bottom of the bottle oh that is where did my plug go all right here's the question do we see the bubble form as I expected bubble okay partial bubble oh man oh that's cool I see a bubble at the start that's doing roughly what I predicted it's moving a little bit toward the nozzle side of this static rocket test and then as soon as the plug blows out we see the same behavior of the unobstructed tests which is the flame suddenly starts having a much harder time move moving backward in the bottle in fact we see the fire spring forward suddenly as the obstruction is blown out which shows how that pressure in the back of the bottle when the obstruction is in the front the pressure the pressure inside the bottle is roughly equal as soon as this blows out it's much harder for the fire to travel backwards than it is in the direction that the flow is going out of the nozzle so I guess what we need to do is we need to test different ignition points now we need to test at the back of the bottle and toward the nozzle and see what the difference is I have a feeling that putting the ignition point closer to the nozzle is going to cause the bottle to melt really quickly because as we've seen it's hard for that flame to move backwards and so it's gonna take a long time to burn and that causes a lot of heat to be transferred to the bottle over that long duration burn time all right let's try it let's see what happens all right ignition point about one inch from the end let's see what happens oh there we go beautiful beautiful slow burn all the way to the end of the bottle so from this shot you can see that that differential of pressure that was happening in the bottles when we were igniting them in the center just doesn't occur here it's all it's all a steady gradient of flame front travelling through the bottle because you don't have that that flow opposite the ignition point where you get that that flame traveling quickly toward the nozzle it's all just steadily burning toward that a high-pressure area in the back and that just it just makes such an even thrust throughout the burn this is like an end burning or an end grain rocket which would be like a traditional kind of rocket a solid fuel rocket I've made black-powder rockets in the past and this is how you would make an end burning black-powder rocket you'd ignite it right at the nozzle and then you get a steady burn all the way to the end all right so my prediction for this test is that with the ignition point at the back of the bottle the expanding explosion is going to push a lot of the propane out of the end of the nozzle before it has a chance to ignite and we'll see a big explosion of propane in the open air out here that's what I'm thinking is going to happen but obviously my predictions have already been wrong once before today so let's see what happens okay that is not what I was expecting the vigorousness of that explosion is obviously indicative that I had the fuel air mixture just right it's gonna take the high speed to really know what just happened okay I'm gonna try this again but this time I'm going to make it a little bit more fuel rich so that we have a slower burn and hopefully that will allow us to see the flame effects in more detail because they will happen more slowly all right three two one good gravy all right I think they call that a mission failure for the less ideal fuel mixture I think that was still plenty of oxygen mixing with that fuel lesson learned here is that if you want a very rapid burn in these bottles ignite them far away from the nozzle high speed is just an explosion it shows nothing it shows nothing at all that I there is no way I am going to put an obstruction in this bottle and ignite it from the back like that because that explosion is way too energetic and it'll send this thing probably right through the wall of my barn I don't really want to deal with that by the way you might think this camera looks all fancy and expensive but this thing has been beaten to crap you can see mid chute already in this video I had to take out the power switch I had to open the whole thing up because the switch failed and solder on thise two wires so to turn this camera on and off now I have to twist these wires together so what I think we learned from the previous set of tests is that most of the interesting things that happen with the flame propagation happened when we have the ignition point in the middle of the bottle or toward the nozzle it's a little too vigorous to see any specific thing going on when we have the ignition point at the end and it's a little too vigorous for my comfort here in my studio so what we'll do we'll fill this larger bottle with propane we'll do a central ignition point first and we will also do an unobscured and then an obscured test and see if the effects are any more exaggerated in this larger bottle and see if we learn anything new alright let's do it three two one Wow now one thing that I noticed straight away before I even see what the high-speed looks like is I saw the the water vapor deposit on the sides of the bottle in a flame pattern so I know we got some wavy looking flames toward the back of the bottle and let's see and we did that was awesome oh man oh I gotta wait for it to finish processing before I can wash it again that's the worst part about high speed video recording I did not mean to hit the trigger fortunately I did not mean to hit the trigger but you got to see in that shot how the rate of combustion of propane when it's in this sort of confined State you don't really have to worry about the heat I'm totally uninjured no burns to my fingers or anything I'm totally fine just that startled me something fierce okay oh man I made such a face in that shot now I'm remembering the last video I filmed with propane explosions this kind of stuff makes me happy I'm having fun with this video and in three two one all right beautiful that's exactly what we saw in the smaller bottle on the front end of the ignition point on the nozzle end we start to see that rapid acceleration of the flame it's just blasting toward the nozzle and on the back you have that higher pressure area and the flames just moving slower just toward that back section of the of the container that's it all right so we've seen exactly how this works let's move again to the front of the launcher no no no no no I haven't done the obstruction yet in this bottle let's try that there it is this by the way if you didn't understand from earlier in the video is meant to simulate what this model would be like if I actually had it loaded onto one of my bottle launcher projects this is like the barrel of my bottle launchers and simulates how the burn should be if I were actually firing this bottle into the sky okay test is ready obstruction is in place let's see what happens three two one good gravy Wow Wow oh man I can't wait to see what that looked like on high speed we blew the whole front end off the bottle the tape definitely did not hold okay we have learned that packaging tape definitely does not hold for a bottle of this size when there is an obstruction in the nozzle wow that was awesome don't try this at home you know what for this size a bottle I think that obstruction just could not get out of the way fast enough and the pressure built up too high inside the bottle for this plastic joint to hold now I bet a bottle made with the water rocket method with a glued joint would have actually held because the combustion of propane if it's not compressed beforehand can only generate like 50 or 60 psi and a soda bottle that has meant for carbonated beverages can hold about 200 psi so the bottle itself would have no trouble holding this force I think this tape joint is just too weak so obviously with the obstruction that was just too much pressure inside of this bottle when the ignition point is in the center but I bet when we now move on to the ignition point being closer to the nozzle since we get that steadier burn as it moves backward into the higher pressure area maybe we can slow down the burn enough to make the pressure manageable with these taped joints even with the obstruction in place okay unobstructed test nozzle ignition point let's see what happens oh I could see that even without the slow motion nice slow burn wave of fire moving backwards into the high pressure area in the bottle now in this shot you can see how slow that flame moves and that is exactly why the end of the bottle melts so quickly in this sort of shot when it was not melting when we were doing the center ignition tests that slow flame gives a long duration for the the heat to be acting upon the plastic and that's how you get the heat transfer that duration of burn okay I think this will be my last test for the evening we are going to do a nozzle and ignition and we are going to have the obstruction in place I think the tape will hold because of that endpoint ignition being so much less vigorous than a mid or far end ignition alright final test in three two one and the bottle survives oh that is gorgeous and the bottle survived which means that it's possible that I could get away with these really easy tapes joints on some larger propane bottle rockets if I figure out how to make the ignition be in the proper location in the bottle and actually with that end point ignition it could allow for a longer burn time in the air and maybe a longer flight time of the bottles we'll have to experiment more we'll have to put these on a real launcher and see how high we can get them with some fins and maybe a parachute all right [Music] this video was sponsored by an Bell science who offers subscription-based chemistry sets and experiments delivered right to your door the free starter kit along with each set of experiments comes with everything needed to make spectacular chemistry happen if you have young family members it's a great way to encourage an interest in chemistry while also spending meaningful time together the instructions are easy to follow especially when using the mobile app assistant with detailed explanations of the chemistry involved as experiments are completed there's more learning accessible through mel chemistry vr lessons using the free VR headset that comes with the starter kit check out mel science and get a 25% discount on mel chemistry sets by using my link in the video description below thanks for watching this video I hope you enjoyed it see you next time [Music] [Music]

Channel: NightHawkInLight

Views: 512,627

Keywords: Rockets, Rocketry, Science Experiments, Experiments, Science, Fire, Propane, Bottle Rockets, Soda Bottle Rockets, Water Rockets, NightHawkInLight

Id: jbuDYitVRuo

Length: 19min 31sec (1171 seconds)

Published: Thu Dec 05 2019